Answer
The missing dimension of the shaft is 5 inches.
Work Step by Step
To find the missing dimension of the shaft, all you need to do is subtract all the pieces you know the lengths of from the total length of the shaft.
So, m.d. = missing dimension.
m.d. = 7$\frac{1}{8}$in - $\frac{7}{8}$in - $\frac{3}{16}$in - $\frac{7}{8}$in - $\frac{3}{16}$in
We can write 7$\frac{1}{8}$ as 7 + $\frac{1}{8}$.
=> m.d. = 7in + $\frac{1}{8}$in - $\frac{7}{8}$in - $\frac{3}{16}$in - $\frac{7}{8}$in - $\frac{3}{16}$in.
Our maximum common divisor in this case is 16.
=> m.d. = 7in + $\frac{2(1)-2(7)-3-7(2)-3}{16}$in = 7 in - 2 in = 5 in
So the missing dimension of the shaft is 5 inches.